X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Fcommon%2Fevent.cpp;h=f33518eee4eece45c2c8ce762cb22765a682209b;hb=fbc3f258425648821da7264860ca32cc24db0915;hp=8d85a2d7f4ebe9182ac8f077f1ab5d46ec8d6722;hpb=8ddd72efb54e568ddead0aa3fbc05a3ced24da7d;p=lttng-tools.git

diff --git a/src/common/event.cpp b/src/common/event.cpp
index 8d85a2d7f..f33518eee 100644
--- a/src/common/event.cpp
+++ b/src/common/event.cpp
@@ -5,28 +5,28 @@
  *
  */
 
-#include "common/compat/string.h"
-#include "common/macros.h"
-#include "lttng/lttng-error.h"
-#include <assert.h>
-#include <common/buffer-view.h>
-#include <common/dynamic-array.h>
-#include <common/dynamic-buffer.h>
-#include <common/error.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/align.h>
+#include <common/align.hpp>
+#include <common/buffer-view.hpp>
+#include <common/compat/string.hpp>
+#include <common/dynamic-array.hpp>
+#include <common/dynamic-buffer.hpp>
+#include <common/error.hpp>
+#include <common/macros.hpp>
+#include <common/sessiond-comm/sessiond-comm.hpp>
+
 #include <lttng/constant.h>
-#include <lttng/event-internal.h>
+#include <lttng/event-internal.hpp>
 #include <lttng/event.h>
-#include <lttng/userspace-probe-internal.h>
-#include <stdint.h>
-#include <string.h>
+#include <lttng/lttng-error.h>
+#include <lttng/userspace-probe-internal.hpp>
 
+namespace {
 struct event_list_element {
 	struct lttng_event *event;
 	struct lttng_event_exclusion *exclusions;
 	char *filter_expression;
 };
+} /* namespace */
 
 static void event_list_destructor(void *ptr)
 {
@@ -43,7 +43,7 @@ struct lttng_event *lttng_event_copy(const struct lttng_event *event)
 	struct lttng_event *new_event;
 	struct lttng_event_extended *new_event_extended;
 
-	new_event = (lttng_event *) zmalloc(sizeof(*event));
+	new_event = zmalloc<lttng_event>();
 	if (!new_event) {
 		PERROR("Error allocating event structure");
 		goto end;
@@ -56,7 +56,7 @@ struct lttng_event *lttng_event_copy(const struct lttng_event *event)
 	 * We need to create a new extended since the previous pointer is now
 	 * invalid.
 	 */
-	new_event_extended = (lttng_event_extended *) zmalloc(sizeof(*new_event_extended));
+	new_event_extended = zmalloc<lttng_event_extended>();
 	if (!new_event_extended) {
 		PERROR("Error allocating event extended structure");
 		goto error;
@@ -77,10 +77,11 @@ static int lttng_event_probe_attr_serialize(
 {
 	int ret;
 	size_t symbol_name_len;
-	struct lttng_event_probe_attr_comm comm = { 0 };
+	struct lttng_event_probe_attr_comm comm = {};
 
-	symbol_name_len = lttng_strnlen(probe->symbol_name, LTTNG_SYMBOL_NAME_LEN);
-	if (symbol_name_len == LTTNG_SYMBOL_NAME_LEN) {
+	symbol_name_len = lttng_strnlen(
+			probe->symbol_name, sizeof(probe->symbol_name));
+	if (symbol_name_len == sizeof(probe->symbol_name)) {
 		/* Not null-termintated. */
 		ret = -1;
 		goto end;
@@ -112,10 +113,13 @@ static int lttng_event_function_attr_serialize(
 {
 	int ret;
 	size_t symbol_name_len;
-	struct lttng_event_function_attr_comm comm = { 0 };
+	struct lttng_event_function_attr_comm comm;
+
+	comm.symbol_name_len = 0;
 
-	symbol_name_len = lttng_strnlen(function->symbol_name, LTTNG_SYMBOL_NAME_LEN);
-	if (symbol_name_len == LTTNG_SYMBOL_NAME_LEN) {
+	symbol_name_len = lttng_strnlen(
+			function->symbol_name, sizeof(function->symbol_name));
+	if (symbol_name_len == sizeof(function->symbol_name)) {
 		/* Not null-termintated. */
 		ret = -1;
 		goto end;
@@ -157,8 +161,7 @@ static ssize_t lttng_event_probe_attr_create_from_payload(
 	comm = (typeof(comm)) comm_view.buffer.data;
 	offset += sizeof(*comm);
 
-	local_attr = (struct lttng_event_probe_attr *) zmalloc(
-			sizeof(*local_attr));
+	local_attr = zmalloc<lttng_event_probe_attr>();
 	if (local_attr == NULL) {
 		ret = -1;
 		goto end;
@@ -187,7 +190,7 @@ static ssize_t lttng_event_probe_attr_create_from_payload(
 		}
 
 		ret = lttng_strncpy(local_attr->symbol_name, name,
-				LTTNG_SYMBOL_NAME_LEN);
+				sizeof(local_attr->symbol_name));
 		if (ret) {
 			ret = -1;
 			goto end;
@@ -200,6 +203,7 @@ static ssize_t lttng_event_probe_attr_create_from_payload(
 	local_attr = NULL;
 	ret = offset;
 end:
+	free(local_attr);
 	return ret;
 }
 
@@ -221,8 +225,7 @@ static ssize_t lttng_event_function_attr_create_from_payload(
 	comm = (typeof(comm)) view->buffer.data;
 	offset += sizeof(*comm);
 
-	local_attr = (struct lttng_event_function_attr *) zmalloc(
-			sizeof(*local_attr));
+	local_attr = zmalloc<lttng_event_function_attr>();
 	if (local_attr == NULL) {
 		ret = -1;
 		goto end;
@@ -248,7 +251,7 @@ static ssize_t lttng_event_function_attr_create_from_payload(
 		}
 
 		ret = lttng_strncpy(local_attr->symbol_name, name,
-				LTTNG_SYMBOL_NAME_LEN);
+				sizeof(local_attr->symbol_name));
 		if (ret) {
 			ret = -1;
 			goto end;
@@ -261,6 +264,7 @@ static ssize_t lttng_event_function_attr_create_from_payload(
 	local_attr = NULL;
 	ret = offset;
 end:
+	free(local_attr);
 	return ret;
 }
 
@@ -270,12 +274,12 @@ static ssize_t lttng_event_exclusions_create_from_payload(
 		struct lttng_event_exclusion **exclusions)
 {
 	ssize_t ret, offset = 0;
-	size_t size = (count * LTTNG_SYMBOL_NAME_LEN);
+	const size_t size = (count * LTTNG_SYMBOL_NAME_LEN);
 	uint32_t i;
 	const struct lttng_event_exclusion_comm *comm;
 	struct lttng_event_exclusion *local_exclusions;
 
-	local_exclusions = (struct lttng_event_exclusion *) zmalloc(
+	local_exclusions = zmalloc<lttng_event_exclusion>(
 			sizeof(struct lttng_event_exclusion) + size);
 	if (!local_exclusions) {
 		ret = -1;
@@ -315,8 +319,8 @@ static ssize_t lttng_event_exclusions_create_from_payload(
 			goto end;
 		}
 
-		ret = lttng_strncpy(local_exclusions->names[i],
-				string, LTTNG_SYMBOL_NAME_LEN);
+		ret = lttng_strncpy(LTTNG_EVENT_EXCLUSION_NAME_AT(local_exclusions, i), string,
+				sizeof(LTTNG_EVENT_EXCLUSION_NAME_AT(local_exclusions, i)));
 		if (ret) {
 			ret = -1;
 			goto end;
@@ -404,8 +408,8 @@ ssize_t lttng_event_create_from_payload(struct lttng_payload_view *view,
 			goto end;
 		}
 
-		ret = lttng_strncpy(
-				local_event->name, name, LTTNG_SYMBOL_NAME_LEN);
+		ret = lttng_strncpy(local_event->name, name,
+				sizeof(local_event->name));
 		if (ret) {
 			ret = -1;
 			goto end;
@@ -508,8 +512,7 @@ deserialize_filter_expression:
 			goto end;
 		}
 
-		local_bytecode = (struct lttng_bytecode *) zmalloc(
-				event_comm->bytecode_len);
+		local_bytecode = zmalloc<lttng_bytecode>(event_comm->bytecode_len);
 		if (!local_bytecode) {
 			ret = -1;
 			goto end;
@@ -619,7 +622,7 @@ deserialize_event_type_payload:
 		}
 
 		if (ret != event_comm->userspace_probe_location_len) {
-			WARN("Userspace probe location from the received buffer is not the advertised length: header length = %" PRIu32 ", payload length = %lu", event_comm->userspace_probe_location_len, ret);
+			WARN("Userspace probe location from the received buffer is not the advertised length: header length = %" PRIu32 ", payload length = %zd", event_comm->userspace_probe_location_len, ret);
 			ret = -1;
 			goto end;
 		}
@@ -698,7 +701,7 @@ int lttng_event_serialize(const struct lttng_event *event,
 	unsigned int i;
 	size_t header_offset, size_before_payload;
 	size_t name_len;
-	struct lttng_event_comm event_comm = { 0 };
+	struct lttng_event_comm event_comm = {};
 	struct lttng_event_comm *header;
 
 	assert(event);
@@ -708,8 +711,8 @@ int lttng_event_serialize(const struct lttng_event *event,
 	/* Save the header location for later in-place header update. */
 	header_offset = payload->buffer.size;
 
-	name_len = lttng_strnlen(event->name, LTTNG_SYMBOL_NAME_LEN);
-	if (name_len == LTTNG_SYMBOL_NAME_LEN) {
+	name_len = lttng_strnlen(event->name, sizeof(event->name));
+	if (name_len == sizeof(event->name)) {
 		/* Event name is not NULL-terminated. */
 		ret = -1;
 		goto end;
@@ -763,9 +766,9 @@ int lttng_event_serialize(const struct lttng_event *event,
 	for (i = 0; i < exclusion_count; i++) {
 		const size_t exclusion_len = lttng_strnlen(
 				*(exclusion_list + i), LTTNG_SYMBOL_NAME_LEN);
-		const struct lttng_event_exclusion_comm exclusion_header = {
-			.len = (uint32_t) exclusion_len + 1,
-		};
+		struct lttng_event_exclusion_comm exclusion_header;
+
+		exclusion_header.len = (uint32_t) exclusion_len + 1;
 
 		if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
 			/* Exclusion is not NULL-terminated. */
@@ -886,6 +889,593 @@ end:
 	return ret;
 }
 
+static ssize_t lttng_event_context_app_populate_from_payload(
+		const struct lttng_payload_view *view,
+		struct lttng_event_context *event_ctx)
+{
+	ssize_t ret, offset = 0;
+	const struct lttng_event_context_app_comm *comm;
+	char *provider_name = NULL, *context_name = NULL;
+	size_t provider_name_len, context_name_len;
+	const struct lttng_buffer_view comm_view = lttng_buffer_view_from_view(
+			&view->buffer, offset, sizeof(*comm));
+
+	assert(event_ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
+
+	if (!lttng_buffer_view_is_valid(&comm_view)) {
+		ret = -1;
+		goto end;
+	}
+
+	comm = (typeof(comm)) comm_view.data;
+	offset += sizeof(*comm);
+
+	provider_name_len = comm->provider_name_len;
+	context_name_len = comm->ctx_name_len;
+
+	if (provider_name_len == 0 || context_name_len == 0) {
+		/*
+		 * Application provider and context names MUST
+		 * be provided.
+		 */
+		ret = -1;
+		goto end;
+	}
+
+	{
+		const char *name;
+		const struct lttng_buffer_view provider_name_view =
+				lttng_buffer_view_from_view(&view->buffer,
+						offset,
+						provider_name_len);
+
+		if (!lttng_buffer_view_is_valid(&provider_name_view)) {
+			ret = -1;
+			goto end;
+		}
+
+		name = provider_name_view.data;
+
+		if (!lttng_buffer_view_contains_string(&provider_name_view,
+				name, provider_name_len)) {
+			ret = -1;
+			goto end;
+		}
+
+		provider_name = lttng_strndup(name, provider_name_len);
+		if (!provider_name) {
+			ret = -1;
+			goto end;
+		}
+
+		offset += provider_name_len;
+	}
+
+	{
+		const char *name;
+		const struct lttng_buffer_view context_name_view =
+				lttng_buffer_view_from_view(
+						&view->buffer, offset,
+						context_name_len);
+
+		if (!lttng_buffer_view_is_valid(&context_name_view)) {
+			ret = -1;
+			goto end;
+		}
+
+		name = context_name_view.data;
+
+		if (!lttng_buffer_view_contains_string(&context_name_view, name,
+				    context_name_len)) {
+			ret = -1;
+			goto end;
+		}
+
+		context_name = lttng_strndup(name, context_name_len);
+		if (!context_name) {
+			ret = -1;
+			goto end;
+		}
+
+		offset += context_name_len;
+	}
+
+	/* Transfer ownership of the strings */
+	event_ctx->u.app_ctx.provider_name = provider_name;
+	event_ctx->u.app_ctx.ctx_name = context_name;
+	provider_name = NULL;
+	context_name = NULL;
+
+	ret = offset;
+end:
+	free(provider_name);
+	free(context_name);
+
+	return ret;
+}
+
+static ssize_t lttng_event_context_perf_counter_populate_from_payload(
+		const struct lttng_payload_view *view,
+		struct lttng_event_context *event_ctx)
+{
+	int ret;
+	ssize_t consumed, offset = 0;
+	const struct lttng_event_context_perf_counter_comm *comm;
+	size_t name_len;
+	const struct lttng_buffer_view comm_view = lttng_buffer_view_from_view(
+			&view->buffer, offset, sizeof(*comm));
+
+	assert(event_ctx->ctx == LTTNG_EVENT_CONTEXT_PERF_COUNTER ||
+			event_ctx->ctx ==
+					LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER ||
+			event_ctx->ctx == LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER);
+
+	if (!lttng_buffer_view_is_valid(&comm_view)) {
+		consumed = -1;
+		goto end;
+	}
+
+	comm = (typeof(comm)) comm_view.data;
+	offset += sizeof(*comm);
+
+	name_len = comm->name_len;
+
+	{
+		const char *name;
+		const struct lttng_buffer_view provider_name_view =
+				lttng_buffer_view_from_view(
+						&view->buffer, offset,
+						name_len);
+
+		if (!lttng_buffer_view_is_valid(&provider_name_view)) {
+			consumed = -1;
+			goto end;
+		}
+
+		name = provider_name_view.data;
+
+		if (!lttng_buffer_view_contains_string(
+				    &provider_name_view, name, name_len)) {
+			consumed = -1;
+			goto end;
+		}
+
+		ret = lttng_strncpy(event_ctx->u.perf_counter.name, name,
+				sizeof(event_ctx->u.perf_counter.name));
+		if (ret) {
+			consumed = -1;
+			goto end;
+		}
+		offset += name_len;
+	}
+
+	event_ctx->u.perf_counter.config = comm->config;
+	event_ctx->u.perf_counter.type = comm->type;
+
+	consumed = offset;
+
+end:
+	return consumed;
+}
+
+ssize_t lttng_event_context_create_from_payload(
+		struct lttng_payload_view *view,
+		struct lttng_event_context **event_ctx)
+{
+	ssize_t ret, offset = 0;
+	const struct lttng_event_context_comm *comm;
+	struct lttng_event_context *local_context = NULL;
+	struct lttng_buffer_view comm_view = lttng_buffer_view_from_view(
+			&view->buffer, offset, sizeof(*comm));
+
+	assert(event_ctx);
+	assert(view);
+
+	if (!lttng_buffer_view_is_valid(&comm_view)) {
+		ret = -1;
+		goto end;
+	}
+
+	comm = (typeof(comm)) comm_view.data;
+	offset += sizeof(*comm);
+
+	local_context = zmalloc<lttng_event_context>();
+	if (!local_context) {
+		ret = -1;
+		goto end;
+	}
+
+	local_context->ctx = (lttng_event_context_type) comm->type;
+
+	{
+		struct lttng_payload_view subtype_view =
+				lttng_payload_view_from_view(view, offset, -1);
+
+		switch (local_context->ctx) {
+		case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
+			ret = lttng_event_context_app_populate_from_payload(
+					&subtype_view, local_context);
+			break;
+		case LTTNG_EVENT_CONTEXT_PERF_COUNTER:
+		case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
+		case LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER:
+			ret = lttng_event_context_perf_counter_populate_from_payload(
+					&subtype_view, local_context);
+			break;
+		default:
+			/* Nothing else to deserialize. */
+			ret = 0;
+			break;
+		}
+	}
+
+	if (ret < 0) {
+		goto end;
+	}
+
+	offset += ret;
+
+	*event_ctx = local_context;
+	local_context = NULL;
+	ret = offset;
+
+end:
+	free(local_context);
+	return ret;
+}
+
+static int lttng_event_context_app_serialize(
+		struct lttng_event_context *context,
+		struct lttng_payload *payload)
+{
+	int ret;
+	struct lttng_event_context_app_comm comm = {};
+	size_t provider_len, ctx_len;
+	const char *provider_name;
+	const char *ctx_name;
+
+	assert(payload);
+	assert(context);
+	assert(context->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
+
+	provider_name = context->u.app_ctx.provider_name;
+	ctx_name = context->u.app_ctx.ctx_name;
+
+	if (!provider_name || !ctx_name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	provider_len = strlen(provider_name);
+	if (provider_len == 0) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	/* Include the null terminator. */
+	provider_len += 1;
+	comm.provider_name_len = provider_len;
+
+	ctx_len = strlen(ctx_name);
+	if (ctx_len == 0) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	/* Include the null terminator. */
+	ctx_len += 1;
+	comm.ctx_name_len = ctx_len;
+
+	/* Header */
+	ret = lttng_dynamic_buffer_append(&payload->buffer, &comm,
+			sizeof(comm));
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(&payload->buffer, provider_name,
+			provider_len);
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(&payload->buffer, ctx_name,
+			ctx_len);
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+end:
+	return ret;
+}
+
+static int lttng_event_context_perf_counter_serialize(
+		struct lttng_event_perf_counter_ctx *context,
+		struct lttng_payload *payload)
+{
+	int ret;
+	struct lttng_event_context_perf_counter_comm comm = {};
+
+	assert(payload);
+	assert(context);
+
+	comm.config = context->config;
+	comm.type = context->type;
+	comm.name_len = lttng_strnlen(context->name, sizeof(context->name));
+
+	if (comm.name_len == sizeof(context->name)) {
+		ret = -1;
+		goto end;
+	}
+
+	/* Include the null terminator. */
+	comm.name_len += 1;
+
+	/* Header */
+	ret = lttng_dynamic_buffer_append(&payload->buffer, &comm,
+			sizeof(comm));
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(&payload->buffer, context->name,
+			comm.name_len);
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+end:
+	return ret;
+}
+
+int lttng_event_context_serialize(struct lttng_event_context *context,
+		struct lttng_payload *payload)
+{
+	int ret;
+	struct lttng_event_context_comm context_comm;
+
+	context_comm.type = 0;
+
+	assert(context);
+	assert(payload);
+
+	context_comm.type = (uint32_t) context->ctx;
+
+	/* Header */
+	ret = lttng_dynamic_buffer_append(
+			&payload->buffer, &context_comm, sizeof(context_comm));
+	if (ret) {
+		goto end;
+	}
+
+	switch (context->ctx) {
+	case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
+		ret = lttng_event_context_app_serialize(context, payload);
+		break;
+	case LTTNG_EVENT_CONTEXT_PERF_COUNTER:
+	case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
+	case LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER:
+		ret = lttng_event_context_perf_counter_serialize(
+				&context->u.perf_counter, payload);
+		break;
+	default:
+		/* Nothing else to serialize. */
+		break;
+	}
+
+	if (ret) {
+		goto end;
+	}
+
+end:
+	return ret;
+}
+
+void lttng_event_context_destroy(struct lttng_event_context *context)
+{
+	if (!context) {
+		return;
+	}
+
+	if (context->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		free(context->u.app_ctx.provider_name);
+		free(context->u.app_ctx.ctx_name);
+	}
+
+	free(context);
+}
+
+/*
+ * This is a specialized populate for lttng_event_field since it ignores
+ * the extension field of the lttng_event struct and simply copies what it can
+ * to the internal struct lttng_event of a lttng_event_field.
+ */
+static void lttng_event_field_populate_lttng_event_from_event(
+		const struct lttng_event *src, struct lttng_event *destination)
+{
+	memcpy(destination, src, sizeof(*destination));
+
+	/* Remove all possible dynamic data from the destination event rule. */
+	destination->extended.ptr = NULL;
+}
+
+ssize_t lttng_event_field_create_from_payload(
+		struct lttng_payload_view *view,
+		struct lttng_event_field **field)
+{
+	ssize_t ret, offset = 0;
+	struct lttng_event_field *local_event_field = NULL;
+	struct lttng_event *event = NULL;
+	const struct lttng_event_field_comm *comm;
+	const char* name = NULL;
+
+	assert(field);
+	assert(view);
+
+	{
+		const struct lttng_buffer_view comm_view =
+				lttng_buffer_view_from_view(
+						&view->buffer, offset,
+						sizeof(*comm));
+
+		if (!lttng_buffer_view_is_valid(&comm_view)) {
+			ret = -1;
+			goto end;
+		}
+
+		/* lttng_event_field_comm header */
+		comm = (const lttng_event_field_comm *) comm_view.data;
+		offset += sizeof(*comm);
+	}
+
+	local_event_field = zmalloc<lttng_event_field>();
+	if (!local_event_field) {
+		ret = -1;
+		goto end;
+	}
+
+	local_event_field->type = (lttng_event_field_type) comm->type;
+	local_event_field->nowrite = comm->nowrite;
+
+	/* Field name */
+	{
+		const struct lttng_buffer_view name_view =
+				lttng_buffer_view_from_view(
+						&view->buffer, offset,
+						comm->name_len);
+
+		if (!lttng_buffer_view_is_valid(&name_view)) {
+			ret = -1;
+			goto end;
+		}
+
+		name = name_view.data;
+
+		if (!lttng_buffer_view_contains_string(&name_view,
+				name_view.data, comm->name_len)) {
+			ret = -1;
+			goto end;
+		}
+
+		if (comm->name_len > LTTNG_SYMBOL_NAME_LEN - 1) {
+			/* Name is too long.*/
+			ret = -1;
+			goto end;
+		}
+
+		offset += comm->name_len;
+	}
+
+	/* Event */
+	{
+		struct lttng_payload_view event_view =
+				lttng_payload_view_from_view(
+						view, offset,
+						comm->event_len);
+
+		if (!lttng_payload_view_is_valid(&event_view)) {
+			ret = -1;
+			goto end;
+		}
+
+		ret = lttng_event_create_from_payload(&event_view, &event, NULL,
+				NULL, NULL);
+		if (ret != comm->event_len) {
+			ret = -1;
+			goto end;
+		}
+
+		offset += ret;
+	}
+
+	assert(name);
+	assert(event);
+
+	if (lttng_strncpy(local_event_field->field_name, name,
+			sizeof(local_event_field->field_name))) {
+		ret = -1;
+		goto end;
+	}
+
+	lttng_event_field_populate_lttng_event_from_event(
+			event, &local_event_field->event);
+
+	*field = local_event_field;
+	local_event_field = NULL;
+	ret = offset;
+end:
+	lttng_event_destroy(event);
+	free(local_event_field);
+	return ret;
+}
+
+int lttng_event_field_serialize(const struct lttng_event_field *field,
+		struct lttng_payload *payload)
+{
+	int ret;
+	size_t header_offset, size_before_event;
+	size_t name_len;
+	struct lttng_event_field_comm event_field_comm = {};
+	struct lttng_event_field_comm *header;
+
+	assert(field);
+	assert(payload);
+
+	/* Save the header location for later in-place header update. */
+	header_offset = payload->buffer.size;
+
+	name_len = strnlen(field->field_name, sizeof(field->field_name));
+	if (name_len == sizeof(field->field_name)) {
+		/* Event name is not NULL-terminated. */
+		ret = -1;
+		goto end;
+	}
+
+	/* Add null termination. */
+	name_len += 1;
+
+	event_field_comm.type = field->type;
+	event_field_comm.nowrite = (uint8_t)field->nowrite;
+	event_field_comm.name_len = name_len;
+
+	/* Header */
+	ret = lttng_dynamic_buffer_append(
+			&payload->buffer, &event_field_comm,
+			sizeof(event_field_comm));
+	if (ret) {
+		goto end;
+	}
+
+	/* Field name */
+	ret = lttng_dynamic_buffer_append(&payload->buffer, field->field_name,
+			name_len);
+	if (ret) {
+		goto end;
+	}
+
+	size_before_event = payload->buffer.size;
+	ret = lttng_event_serialize(
+			&field->event, 0, NULL, NULL, 0, 0, payload);
+	if (ret) {
+		ret = -1;
+		goto end;
+	}
+
+	/* Update the event len. */
+	header = (struct lttng_event_field_comm *)
+			((char *) payload->buffer.data +
+				header_offset);
+	header->event_len = payload->buffer.size - size_before_event;
+
+end:
+	return ret;
+}
+
 static enum lttng_error_code compute_flattened_size(
 		struct lttng_dynamic_pointer_array *events, size_t *size)
 {
@@ -901,6 +1491,9 @@ static enum lttng_error_code compute_flattened_size(
 	/* The basic struct lttng_event */
 	storage_req = event_count * sizeof(struct lttng_event);
 
+	/* The struct·lttng_event_extended */
+	storage_req += event_count * sizeof(struct lttng_event_extended);
+
 	for (i = 0; i < event_count; i++) {
 		int probe_storage_req = 0;
 		const struct event_list_element *element = (const struct event_list_element *)
@@ -921,10 +1514,6 @@ static enum lttng_error_code compute_flattened_size(
 			probe_storage_req = ret;
 		}
 
-		/* The struct·lttng_event_extended */
-		storage_req += event_count *
-			sizeof(struct lttng_event_extended);
-
 		if (element->filter_expression) {
 			storage_req += strlen(element->filter_expression) + 1;
 		}
@@ -1125,8 +1714,7 @@ static enum lttng_error_code event_list_create_from_payload(
 		ssize_t event_size;
 		struct lttng_payload_view event_view =
 				lttng_payload_view_from_view(view, offset, -1);
-		struct event_list_element *element =
-				(struct event_list_element *) zmalloc(sizeof(*element));
+		struct event_list_element *element = zmalloc<event_list_element>();
 
 		if (!element) {
 			ret_code = LTTNG_ERR_NOMEM;
@@ -1203,3 +1791,158 @@ end:
 	lttng_dynamic_pointer_array_reset(&local_events);
 	return ret;
 }
+
+static enum lttng_error_code flatten_lttng_event_fields(
+		struct lttng_dynamic_pointer_array *event_fields,
+		struct lttng_event_field **flattened_event_fields)
+{
+	int ret, i;
+	enum lttng_error_code ret_code;
+	size_t storage_req = 0;
+	struct lttng_dynamic_buffer local_flattened_event_fields;
+	int nb_event_field;
+
+	assert(event_fields);
+	assert(flattened_event_fields);
+
+	lttng_dynamic_buffer_init(&local_flattened_event_fields);
+	nb_event_field = lttng_dynamic_pointer_array_get_count(event_fields);
+
+	/*
+	 * Here even if the event field contains a `struct lttng_event` that
+	 * could contain dynamic data, in reality it is not the case.
+	 * Dynamic data is not present. Here the flattening is mostly a direct
+	 * memcpy. This is less than ideal but this code is still better than
+	 * direct usage of an unpacked lttng_event_field array.
+	 */
+	storage_req += sizeof(struct lttng_event_field) * nb_event_field;
+
+	lttng_dynamic_buffer_init(&local_flattened_event_fields);
+
+	/*
+	 * We must ensure that "local_flattened_event_fields" is never resized
+	 * so as to preserve the validity of the flattened objects.
+	 */
+	ret = lttng_dynamic_buffer_set_capacity(
+			&local_flattened_event_fields, storage_req);
+	if (ret) {
+		ret_code = LTTNG_ERR_NOMEM;
+		goto end;
+	}
+
+	for (i = 0; i < nb_event_field; i++) {
+		const struct lttng_event_field *element =
+				(const struct lttng_event_field *)
+					lttng_dynamic_pointer_array_get_pointer(
+						event_fields, i);
+
+		if (!element) {
+			ret_code = LTTNG_ERR_FATAL;
+			goto end;
+		}
+		ret = lttng_dynamic_buffer_append(&local_flattened_event_fields,
+				element, sizeof(struct lttng_event_field));
+		if (ret) {
+			ret_code = LTTNG_ERR_NOMEM;
+			goto end;
+		}
+	}
+
+	/* Don't reset local_flattened_channels buffer as we return its content. */
+	*flattened_event_fields = (struct lttng_event_field *) local_flattened_event_fields.data;
+	lttng_dynamic_buffer_init(&local_flattened_event_fields);
+	ret_code = LTTNG_OK;
+end:
+	lttng_dynamic_buffer_reset(&local_flattened_event_fields);
+	return ret_code;
+}
+
+static enum lttng_error_code event_field_list_create_from_payload(
+		struct lttng_payload_view *view,
+		unsigned int count,
+		struct lttng_dynamic_pointer_array **event_field_list)
+{
+	enum lttng_error_code ret_code;
+	int ret, offset = 0;
+	unsigned int i;
+	struct lttng_dynamic_pointer_array *list = NULL;
+
+	assert(view);
+	assert(event_field_list);
+
+	list = zmalloc<lttng_dynamic_pointer_array>();
+	if (!list) {
+		ret_code = LTTNG_ERR_NOMEM;
+		goto end;
+	}
+
+	lttng_dynamic_pointer_array_init(list, free);
+
+	for (i = 0; i < count; i++) {
+		ssize_t event_field_size;
+		struct lttng_event_field *field = NULL;
+		struct lttng_payload_view event_field_view =
+				lttng_payload_view_from_view(view, offset, -1);
+
+		event_field_size = lttng_event_field_create_from_payload(
+				&event_field_view, &field);
+		if (event_field_size < 0) {
+			ret_code = LTTNG_ERR_INVALID;
+			goto end;
+		}
+
+		/* Lifetime and management of the object is now bound to the array. */
+		ret = lttng_dynamic_pointer_array_add_pointer(list, field);
+		if (ret) {
+			free(field);
+			ret_code = LTTNG_ERR_NOMEM;
+			goto end;
+		}
+
+		offset += event_field_size;
+	}
+
+	if (view->buffer.size != offset) {
+		ret_code = LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	*event_field_list = list;
+	list = NULL;
+	ret_code = LTTNG_OK;
+
+end:
+	if (list) {
+		lttng_dynamic_pointer_array_reset(list);
+		free(list);
+	}
+
+	return ret_code;
+}
+
+enum lttng_error_code lttng_event_fields_create_and_flatten_from_payload(
+		struct lttng_payload_view *view,
+		unsigned int count,
+		struct lttng_event_field **fields)
+{
+	enum lttng_error_code ret_code;
+	struct lttng_dynamic_pointer_array *local_event_fields = NULL;
+
+	ret_code = event_field_list_create_from_payload(
+			view, count, &local_event_fields);
+	if (ret_code != LTTNG_OK) {
+		goto end;
+	}
+
+	ret_code = flatten_lttng_event_fields(local_event_fields, fields);
+	if (ret_code != LTTNG_OK) {
+		goto end;
+	}
+end:
+	if (local_event_fields) {
+		lttng_dynamic_pointer_array_reset(local_event_fields);
+		free(local_event_fields);
+	}
+
+	return ret_code;
+}